This application is submitted in response to PA-07-082 (Risk Factors for Psychopathology Using Existing Data Sets) to examine the relationship between migration to the US and mental health in the transnational Mexican- origin population. Previous epidemiological studies have shown that in this population immigration to the US is associated with large increases in risk for psychiatric disorders. At the same time, studies of mental health service use have found significant disparities in the treatment Mexican-Americans receive relative to the majority US population. However, studies conducted in the US are limited in their ability to understand the impact of immigration because of the lack of data on the immigrant source population. Moreover, the Mexican- origin population is a transnational one, tied together across the international border through return migrations, cash remittances sent to families in Mexico, and well maintained social networks that transmit mutual cultural and social influences. Our preliminary work, now in press, suggests that migration to the US has a large impact on mental health in the Mexican population. We propose to construct and analyze a cross-national dataset on mental health and mental health service use in the transnational Mexican-origin population, taking advantage of a unique situation where population based surveys of psychiatric disorders have recently been completed in a nationally representative sample of Mexico and in a nationally representative sample of the Mexican- American population of the US during the same time period, using the same survey instrument, consistent interview methodologies, and uniform interviewer training standards. The research team is comprised of a group in the US with extensive experience studying mental health among Mexican-Americans and a group in Mexico with extensive experience studying mental health in Mexico. Using this unique dataset we will describe patterns of current mental health and mental health service use associated with migration to the US in this transnational population. We will then examine the impact of migration on mental health on both sides of the border, by testing whether migration to the US is associated with risk for psychiatric disorders among the Mexican-American population of the US and whether return migration or transnational family networks are associated with increased risk among those in Mexico. We will also examine whether migration to the US affects the cultural orientation to mental health problems as issues of medical concern, using data on actual service use, perceived need for care and willingness to seek treatment for a mental health problem. Results of these analyses will contribute to etiological understanding of psychiatric disorders by directly examining the relationship between migration and mental health in the context of the largest international migration in the world today and to policy studies that aim to improve mental health care for this underserved population. PUBLIC HEALTH RELEVANCE: Risk for psychiatric disorders and use of mental health services vary dramatically across countries and between immigrants to the US and their US-born descendants, but no studies have yet compared the mental health of immigrants to the US with the population of their country of origin. We propose to fill this gap by combining data from two recent mental health surveys that used consistent methodologies, one on the Mexican population and the other on Mexican-Americans in the US. This study will help identify environmental factors in the etiology of psychiatric disorders and inform policies that aim to improve mental health care for underserved communities in both Mexico and the US.